Deterministic Chaos in Infinite Quantum Systems

Robert H. Parmenter, Lun Yu

Robert H. Parmenter, R.W. Valentine

Uwe Schwengelbeck, Farhad H. M. Faisal

The phenomenon of transition from regular to chaotic dynamics in a periodically driven quantum system is demonstrated. The associated quantum Lyapunov numbers are determined analytically. A numerical experiment is made to test the nature of time evolution predicted by the theory. In contrast to the evolution in the regular domain, the passage to deterministic quantum chaos is found to break the time-reversal symmetry of the quantum dynamics, whenever the latter cannot be followed with infinite precision.

A. G. Lazerson, Alexey Alexeevich Boikov

R.W. Valentine

In this thesis, properties of particle trajectories associated with the de Broglie-Bohm causal interpretation of quantum mechanics are studied. These trajectories are shown to exhibit deterministic chaos and adiabatic invariance under certain conditions. The very basic elements of the causal interpretation are presented in the first chapter. These include the equations of motion for the particle and the quantum potential. A brief discussion of the philosophically agreeable features of the theory is also included. In Chapter 2, properties of chaotic systems are studied. We define deterministic chaos for a flow and present methods for calculating the maximum Lyapunov exponent. The properties of the different types of systems and the conditions that lead to chaos in these systems are analyzed. We study in detail the specific example of the two-dimensional harmonic oscillator in Chapter 3. We find that different types of trajectories include those which are periodic and chaotic. The necessary conditions for obtaining chaos are determined for a superposition of stationary states. Systems which are qualitatively similar to the harmonic oscillator are covered in Chapter 4. These include the two-dimensional infinite well, an infinite well bisected by a finite barrier, and a Rydberg atom in an external electromagnetic field. In Chapter 5, the effect of a spin 1/2 wavefunction is considered. The causal equations of motion for a spin 1/2 particle are introduced. We find that chaotic trajectories are easily obtained. The causal analogue of the geometric phase is defined in Chapter 6. This phase is shown to be an adiabatic invariant for periodic trajectories. We define the geometric frequency for both periodic and aperiodic trajectories. Finally, in Chapter 7 we examine trajectories associated with stationary states. We define necessary conditions for chaos to arise in the trajectories. The properties of entangled boson and fermion systems are analyzed.

Casati, Giulio